JSP191 Antibody Conditioning Regimen in MDS/AML Subjects Undergoing Allogenic Hematopoietic Stem Cell Transplantation

This is a Phase 1a/b study to evaluate the safety and tolerability of an antibody

conditioning regimen known as JSP191, in combination with low dose radiation and

fludarabine in subjects with Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia

(AML) undergoing allogenic blood stem cell transplantation.

Blood Stem Cell transplantation offers the only potentially curative therapy for many

forms of Acute Myeloid Leukemia (AML) and for Myelodysplastic Syndrome (MDS). While

standard of care conditioning regimens given prior to blood Stem Cell transplantation,

such as standard TBI/Flu conditioning are well tolerated, they are associated with

increased rates of relapse due to persistence of disease causing Hematopoietic Stem Cells

and insufficient graft versus leukemia effect.

The biological conditioning regimen JSP191 is an antibody that binds to CD117. CD117 is

the receptor for Stem Cell Factor on blood forming cells. CD117 binding to Stem Cell

Factor is critical for survival and maintenance of blood forming stem cells.

The binding of JSP191 to CD117 blocks CD117 from binding to Stem Cell Factor on blood

forming stem cells. In the absence of CD117/Stem Cell Factor binding, hematopoietic stem

cells that are currently occupying the bone marrow niches in MDS/AML patients are

depleted.

This study will investigate the safety and tolerability of adding JSP191 (an anti-CD117

monoclonal antibody therapy) to standard TBI/Flu conditioning regimen in adults with AML

and MDS undergoing hematopoietic stem cell transplant.